Capacitive pressure sensor, method for manufacturing the same and use thereof

Abstract

This invention provides a capacitive pressure sensor, its fabrication method, and its applications. The dielectric layer of the capacitive pressure sensor is a flexible ionomer thin film, and the upper and lower electrodes are electrodes with rigid microstructures, forming a sandwich structure. Under external force, the high-modulus microstructure gradually embeds into the surface of the low-modulus uniform thin film, forming a local embedding deformation path. This allows the deformation space to be gradually released with pressure, significantly reducing stress concentration and delaying deformation saturation. Furthermore, after the microstructure electrode contacts the ionomer thin film, an electrical double-layer capacitor is formed at the interface, giving the sensor high sensitivity. The embedding process ensures continuous change in the contact area, maintaining good linearity even under high pressure. Therefore, the capacitive pressure sensor of this invention has high sensitivity and a wide linear detection range, and has great application potential in pressure sensor fields such as wearable devices, intelligent robots, and medical monitoring equipment.

Description

Technical Field

[0001] This invention belongs to the field of sensor technology, specifically relating to a capacitive pressure sensor, its fabrication method, and its application. Background Technology

[0002] Currently, the mainstream flexible pressure sensors include resistive, piezoelectric, capacitive, and optical waveguide pressure sensors. Among them, flexible capacitive pressure sensors have been widely developed due to their advantages such as low power consumption, dynamic and static response, stable detection signal, and simple structure. They have great potential application value in wearable devices, human-computer interaction, and medical and health monitoring equipment.

[0003] Capacitive flexible pressure sensors typically consist of upper and lower electrodes and a dielectric layer. Under external force, changes in the dielectric layer thickness or effective contact area cause changes in capacitance. Existing capacitive flexible pressure sensor structures include: integral compression type (overall compression of the soft dielectric layer), microstructure co-deformation type (introducing micro-protrusions / pores on the dielectric layer or electrodes to increase the compressible space), and porous sponge / foamed dielectric layer, etc. However, all of these structures have the following shortcomings: in high-pressure regions, the soft dielectric layer is prone to rapid compaction, leading to capacitive response saturation and a narrowing of the linear range; the microstructure may collapse or the contact area change tends to saturate under high pressure; and stress concentration can cause hysteresis and durability issues. Therefore, there is a need to develop a capacitive flexible pressure sensor that can maintain "continuous deformable space" and "continuous contact area evolution" within a high-pressure range, in order to meet the demand for high-performance sensor devices by balancing high sensitivity and a wide linear range. Summary of the Invention

[0004] To overcome the problems existing in the prior art, one objective of this invention is to provide a capacitive pressure sensor. A second objective of this invention is to provide a method for manufacturing the aforementioned capacitive pressure sensor. A third objective of this invention is to provide applications of the aforementioned capacitive pressure sensor. To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of the present invention provides a capacitive pressure sensor, including a dielectric layer and electrodes disposed on both sides of the dielectric layer; The dielectric layer is a flexible ionic liquid-based polymer film; The electrode includes a metal substrate; a rigid protruding microstructure is provided on one side of the metal substrate; the side of the electrode with the rigid protruding microstructure faces the dielectric layer.

[0005] Preferably, the rigid protruding microstructure includes at least one of the following: spherical microstructure, irregular granular microstructure, sheet-like microstructure, sheet-like / conical microstructure, and conical microstructure; Preferably, the metal substrate is a copper foil.

[0006] Preferably, the preparation method of the electrode with a spherical microstructure includes the following steps: using copper foil as the cathode, zinc plate as the anode, and ZnCl2-containing electrolyte as the medium, a constant current electrodeposition method is used to deposit the electrode to obtain the electrode with a spherical microstructure.

[0007] More preferably, the concentration of ZnCl2 in the ZnCl2-containing electrolyte is 0.5-3 mol / L. More preferably, it is 0.7-1.5 mol / L.

[0008] More preferably, in the constant current electrodeposition method, the current density used is 30-100 mA·cm⁻¹. -2 Further, it is 30-60 mA·cm. -2 .

[0009] More preferably, in the constant current electrodeposition method, the deposition time is 1-10 min. More preferably, it is 3-7 min.

[0010] Preferably, the method for preparing an electrode with sheet-like microstructures includes the following steps: using copper foil as the cathode, zinc plate as the anode, and ZnSO4-containing electrolyte as the medium, a constant current electrodeposition method is used to deposit the electrode to obtain an electrode with sheet-like microstructures.

[0011] More preferably, the concentration of ZnCl2 in the ZnSO4-containing electrolyte is 0.3-2 mol / L. More specifically, it is 0.5-1.2 mol / L.

[0012] More preferably, in the constant current electrodeposition method, the current density used is 20-100 mA·cm⁻¹. -2 Further, it is 30-50 mA·cm. -2 .

[0013] More preferably, in the constant current electrodeposition method, the deposition time is 1-10 min. More preferably, it is 3-7 min.

[0014] Preferably, the method for preparing an electrode with irregular granular microstructure includes the following steps: using copper foil as the cathode, zinc plate as the anode, and an electrolyte containing ZnCl2, NH4Cl and H3BO3 as the medium, a constant current electrodeposition method is used to deposit the electrode to obtain an electrode with irregular granular microstructure.

[0015] More preferably, in the electrolyte containing ZnCl2, NH4Cl, and H3BO3, the concentration of ZnCl2 is 0.1-1 mol / L. More preferably, it is 0.2-0.6 mol / L.

[0016] More preferably, in the electrolyte containing ZnCl2, NH4Cl and H3BO3, the concentration of NH4Cl is 1.5-4 mol / L. More specifically, it is 1.7-3 mol / L, for example, 2-2.5 mol / L.

[0017] More preferably, in the electrolyte containing ZnCl2, NH4Cl and H3BO3, the concentration of H3BO3 is 0.1-1 mol / L. More preferably, it is 0.2-0.6 mol / L.

[0018] More preferably, in the constant current electrodeposition method, the current density used is 40-120 mA·cm⁻¹. -2 Further, it is 45-70 mA·cm. -2 .

[0019] More preferably, in the constant current electrodeposition method, the deposition time is 0.5-4 min. More preferably, it is 1-3 min.

[0020] Preferably, the method for preparing an electrode with sheet-like / conical microstructures includes the following steps: using copper foil as the cathode, nickel foam as the anode, and an electrolyte containing NiCl2, NaCl, and H3BO3 as the medium, a constant current electrodeposition method is used to deposit the electrode to obtain an electrode with sheet-like / conical microstructures.

[0021] More preferably, in the electrolyte containing ZnCl2, NH4Cl, and H3BO3, the concentration of ZnCl2 is 0.1-1 mol / L. More preferably, it is 0.2-0.6 mol / L.

[0022] More preferably, in the electrolyte containing ZnCl2, NH4Cl and H3BO3, the concentration of NH4Cl is 1.5-4 mol / L. More specifically, it is 1.7-3 mol / L, for example, 2-2.5 mol / L.

[0023] More preferably, in the electrolyte containing ZnCl2, NH4Cl and H3BO3, the concentration of H3BO3 is 0.1-1 mol / L. More preferably, it is 0.2-0.6 mol / L.

[0024] More preferably, in the constant current electrodeposition method, the current density used is 20-80 mA·cm⁻¹. -2 Further, it is 25-50 mA·cm. -2 .

[0025] More preferably, in the constant current electrodeposition method, the deposition time is 3-7 minutes. More preferably, it is 4-6 minutes.

[0026] More preferably, in the constant current electrodeposition method, the deposition temperature is 50-70°C. More specifically, it is 55-65°C.

[0027] Preferably, the method for preparing an electrode with a pointed conical microstructure includes the following steps: using copper foil as the cathode, nickel foam as the anode, and an electrolyte containing NiCl2, NH4Cl and H3BO3 as the medium, a constant current electrodeposition method is used to deposit the electrode to obtain an electrode with a pointed conical microstructure.

[0028] More preferably, in the electrolyte containing NiCl2, NH4Cl, and H3BO3, the concentration of NiCl2 is 0.1-1 mol / L. More preferably, it is 0.2-0.6 mol / L.

[0029] More preferably, in the electrolyte containing NiCl2, NH4Cl and H3BO3, the concentration of NH4Cl is 0.05-0.5 mol / L. More preferably, it is 0.1-0.2 mol / L.

[0030] More preferably, in the electrolyte containing NiCl2, NH4Cl and H3BO3, the concentration of H3BO3 is 0.5-2 mol / L. More preferably, it is 0.8-1.2 mol / L.

[0031] More preferably, in the constant current electrodeposition method, the current density used is 10-60 mA·cm⁻¹. -2 Further, it is 15-30 mA·cm. -2 .

[0032] More preferably, in the constant current electrodeposition method, the deposition time is 5-10 min. More preferably, it is 6-8 min.

[0033] More preferably, in the constant current electrodeposition method, the deposition temperature is 50-70°C. More specifically, it is 55-65°C.

[0034] Preferably, the raw materials for preparing the flexible ionic liquid-based polymer film include: ionic liquid and thermoplastic polyurethane elastomer.

[0035] More preferably, the ionic liquid includes at least one of imidazole ionic liquids, pyrrole salt ionic liquids, pyridine salt ionic liquids, ammonium salt ionic liquids, and amino acid salt ionic liquids.

[0036] More preferably, the imidazole ionic liquid includes at least one of 1-ethyl-3-methylimidazolium hexafluorophosphate (EMIM[PF6]), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM[BF4]), 1-ethyl-3-methylimidazolium bis(trifluoroformimide) (EMIM[Tf2N]), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM[PF6]), and 1-hexyl-3-methylimidazolium hexafluorophosphate (HMIM[PF6]).

[0037] More preferably, the preparation method of the flexible ionic liquid-based polymer film includes the following steps: mixing an ionic liquid and a thermoplastic polyurethane elastomer, coating the resulting mixed solution onto a substrate, and drying it to obtain the flexible ionic liquid-based polymer film.

[0038] More preferably, the drying temperature is 60-90°C.

[0039] The second aspect of the present invention provides a method for fabricating the capacitive pressure sensor described in the first aspect, comprising the following steps: attaching a flexible ionic liquid-based polymer film to one side of one electrode, and then attaching another electrode to the other side of the flexible ionic liquid-based polymer film, wherein both sides of the flexible ionic liquid-based polymer film have rigid protruding microstructures in contact with the electrodes to form a three-layer structure; and covering and encapsulating the three-layer structure to obtain the capacitive pressure sensor.

[0040] The third aspect of this invention provides the application of the capacitive pressure sensor described in the first aspect in wearable devices, intelligent robots, and medical monitoring devices.

[0041] The beneficial effects of this invention are: This invention provides a capacitive pressure sensor, wherein the dielectric layer is a flexible ionomer thin film, and the upper and lower electrodes are electrodes with rigid microstructures, forming a sandwich structure. Under external force, the high-modulus microstructure gradually embeds into the surface of the low-modulus uniform thin film, forming a local embedding deformation path. Unlike traditional overall compression or microstructure co-deformation, "embedding deformation" relies on local embedding caused by modulus difference, allowing the deformation space to be gradually released with pressure, significantly reducing stress concentration and delaying deformation saturation. Furthermore, after the microstructure electrode contacts the ionomer thin film, an electrical double-layer capacitor is formed at the interface, giving the sensor high sensitivity; while the embedding process ensures continuous change in contact area, maintaining good linearity even under high pressure. Therefore, the capacitive pressure sensor of this invention has high sensitivity and a wide linear detection range, and has great application potential in the field of pressure sensors such as wearable devices, intelligent robots, and medical monitoring equipment. Attached Figure Description

[0042] Figure 1This is a schematic diagram of the fabrication process of a capacitive pressure sensor.

[0043] Figure 2 The images show the microstructures of rigid microstructures with different morphologies in Examples 1-5, where AE corresponds to Examples 1-5 respectively.

[0044] Figure 3 The images show the microstructures of rigid microstructures with different morphologies in Examples 1 and Comparative Examples 1-2.

[0045] Figure 4 This is a schematic cross-sectional view of a capacitive pressure sensor.

[0046] Figure 5 This is a diagram showing the microscopic changes of a capacitive pressure sensor under initial, low-pressure, and high-pressure conditions.

[0047] Figure 6 This diagram illustrates the deformation and capacitance signal changes of a capacitive pressure sensor under initial, low-pressure, and high-pressure conditions.

[0048] Figure 7 The diagram shows the pressure-capacitance performance of the capacitive pressure sensors prepared using different amounts of ionic liquid in Example 1.

[0049] Figure 8 The pressure-capacitance performance diagrams are for sensors assembled with five types of rigid microstructure electrodes in Examples 1-5.

[0050] Figure 9 The pressure-capacitance performance diagrams are for the three sets of sensors used in Example 1 and Comparative Examples 1-2. Detailed Implementation

[0051] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials used in the following embodiments can be obtained from conventional commercial channels or prepared and isolated through simple synthesis; unless otherwise specified, the processes employed are conventional processes in the art.

[0052] Example 1 This embodiment provides a capacitive pressure sensor, the fabrication process of which is illustrated in the diagram below. Figure 1 The specific preparation method is as follows: S1. Constructing a near-spherical rigid microstructure on the surface of copper foil using electrodeposition: Prepare an electrolyte with a concentration of 1 mol / L ZnCl2. Cut copper foil (1 cm × 2 cm) and zinc plate (1 cm × 4 cm) to specific sizes and wash them with distilled water and anhydrous ethanol. Using the copper foil as the cathode, the zinc plate as the anode, and the above electrolyte as the medium, a constant current electrodeposition method (35 mA·cm⁻¹) is employed. -2Deposition was carried out for 5 min. The copper foil with the deposited zinc layer was washed several times with distilled water to remove ionic impurities from the surface, resulting in a near-spherical microstructure electrode. Finally, the electrode was cut to a suitable size for further use.

[0053] The surface of the copper foil was scanned by electron microscopy, and the results are as follows: Figure 2 As shown in A, a spherical microstructure was successfully electrodeposited on the copper foil.

[0054] S2. TPU (model 1185A, 1.2 g) particles, ionic liquid [EMIM]TF2N (0 g, 0.1333 g, 0.3 g, 0.5143 g, 0.8 g), and DMF (6.8 g) were mixed and stirred at room temperature for 8 hours. The prepared mixture was directly poured onto a glass substrate and scraped with a glass rod with a transparent rubber ring (~1 mm height). Then it was dried at 70 °C for 40 min to obtain an ionomer film.

[0055] S3. Using conductive silver paste, two silver-plated copper wires are connected to two microstructure electrodes respectively. Then, the electrodes and ion membrane are assembled in the manner of electrode-ion membrane-electrode according to the sandwich structure. Finally, they are encapsulated with polyimide (PI, 30 mm) tape to make an ion electronic pressure sensor.

[0056] Example 2 This embodiment provides a capacitive pressure sensor, the specific fabrication method of which is as follows: S1. An irregular granular microstructure was constructed on the surface of copper foil using electrodeposition: An electrolyte solution with a concentration of 0.4 mol / L ZnCl2, 2.2 mol / L NH4Cl, and 0.35 mol / L H3BO3 was prepared. Copper foil (1 cm × 2 cm) and zinc plate (1 cm × 4 cm) of a specific size were cut and washed with distilled water and anhydrous ethanol. Using the copper foil as the cathode, the zinc plate as the anode, and the above electrolyte solution as the medium, a constant current electrodeposition method (50 mA·cm⁻¹) was employed. -2 Deposition was carried out for 2 min. The copper foil with the deposited zinc layer was washed several times with distilled water to remove ionic impurities from the surface, resulting in an irregularly shaped granular microstructure electrode. Finally, the electrode was cut to a suitable size for further use.

[0057] The surface of the copper foil was scanned by electron microscopy, and the results are as follows: Figure 2 As shown in B, an irregular granular microstructure was successfully electrodeposited on the copper foil.

[0058] Steps S2 and S3 are the same as in Example 1, wherein the amount of ionic liquid used is 0.5143 g.

[0059] Example 3 This embodiment provides a capacitive pressure sensor, the specific fabrication method of which is as follows: S1. Constructing sheet-like microstructures on the surface of copper foil using electrodeposition: Prepare an electrolyte with a concentration of 0.7 mol / L ZnSO4. Cut copper foil (1 cm × 2 cm) and zinc plate (1 cm × 4 cm) to specific sizes and wash them with distilled water and anhydrous ethanol. Using the copper foil as the cathode, the zinc plate as the anode, and the above electrolyte as the medium, a constant current electrodeposition method (35 mA·cm⁻¹) is employed. -2 Deposition was carried out for 5 min. The copper foil with the deposited zinc layer was washed several times with distilled water to remove ionic impurities from the surface, resulting in a sheet-like microstructure electrode. Finally, the electrode was cut to a suitable size for further use.

[0060] The surface of the copper foil was scanned by electron microscopy, and the results are as follows: Figure 2 The C in the figure shows that sheet-like microstructures were successfully electrodeposited on the copper foil.

[0061] Steps S2 and S3 are the same as in Example 1, wherein the amount of ionic liquid used is 0.5143 g.

[0062] Example 4 This embodiment provides a capacitive pressure sensor, the specific fabrication method of which is as follows: S1. A sheet-like / conical microstructure was constructed on the surface of copper foil using electrodeposition. An electrolyte solution with a concentration of 0.84 mol / L NiCl2, 1.71 mol / L NaCl, and 0.40 mol / L H3BO3 was prepared. Copper foil (1 cm × 2 cm) and nickel foam (1 cm × 4 cm) of a specific size were cut and washed with distilled water and anhydrous ethanol. Using the copper foil as the cathode, the nickel foam as the anode, and the above electrolyte solution as the medium, a constant current electrodeposition method (30 mA·cm⁻¹) was employed. -2 The nickel layer was deposited at 60 °C for 5 min. The copper foil with the deposited nickel layer was washed several times with distilled water to remove surface ionic impurities, resulting in a cone-shaped / sheet-shaped microstructure electrode. Finally, the electrode was cut to a suitable size for further use.

[0063] The surface of the copper foil was scanned by electron microscopy, and the results are as follows: Figure 2 As shown in D, a conical / sheet-shaped microstructure was successfully electrodeposited on the copper foil.

[0064] Steps S2 and S3 are the same as in Example 1, wherein the amount of ionic liquid used is 0.5143 g.

[0065] Example 5 This embodiment provides a capacitive pressure sensor, the specific fabrication method of which is as follows: S1. Conical microstructures were constructed on the surface of copper foil using electrodeposition: An electrolyte with a concentration of 0.42 mol / L NiCl2, 0.19 mol / L NH4Cl, and 0.81 mol / L H3BO3 was prepared. Copper foil (1 cm × 2 cm) and nickel foam (1 cm × 4 cm) of a certain size were cut and washed with distilled water and anhydrous ethanol. Using the copper foil as the cathode, the nickel foam as the anode, and the above electrolyte as the medium, a constant current electrodeposition method (20 mA·cm⁻¹) was employed. -2 The nickel layer was deposited at 60°C for 7 min. The copper foil with the deposited nickel layer was washed several times with distilled water to remove surface ionic impurities, resulting in a pointed cone-shaped microstructure electrode. Finally, the electrode was cut to a suitable size for further use.

[0066] The surface of the copper foil was scanned by electron microscopy, and the results are as follows: Figure 2 As shown in E, a conical microstructure was successfully electrodeposited on the copper foil.

[0067] Steps S2 and S3 are the same as in Example 1, wherein the amount of ionic liquid used is 0.5143 g.

[0068] Comparative Example 1 This comparative example provides a capacitive pressure sensor, the specific fabrication method of which is as follows: S1. Constructing a near-spherical rigid microstructure on the surface of copper foil using electrodeposition: Prepare an electrolyte with a concentration of 1 mol / L ZnCl2. Cut copper foil (1 cm × 2 cm) and zinc plate (1 cm × 4 cm) to specific sizes and wash them with distilled water and anhydrous ethanol. Using the copper foil as the cathode, the zinc plate as the anode, and the above electrolyte as the medium, a constant current electrodeposition method (20 mA·cm⁻¹) is employed. -2 Deposition was carried out for 5 min. The copper foil with the deposited zinc layer was washed several times with distilled water to remove ionic impurities from the surface, resulting in a near-spherical microstructure electrode. Finally, the electrode was cut to a suitable size for further use.

[0069] The surface of the copper foil was scanned by electron microscopy, and the results are as follows: Figure 3 It can be seen that spherical microstructures with insufficient microstructure density were electrodeposited on the copper foil.

[0070] The steps of S2 and S3 are described in Example 1.

[0071] Comparative Example 2 This embodiment provides a capacitive pressure sensor, and the specific fabrication method is as follows: S1. Constructing a near-spherical rigid microstructure on the surface of copper foil using electrodeposition: Prepare an electrolyte with a concentration of 1 mol / L ZnCl2. Cut copper foil (1 cm × 2 cm) and zinc plate (1 cm × 4 cm) to specific sizes and wash them with distilled water and anhydrous ethanol. Using the copper foil as the cathode, the zinc plate as the anode, and the above electrolyte as the medium, a constant current electrodeposition method (50 mA·cm⁻¹) is employed. -2 Deposition was carried out for 5 min. The copper foil with the deposited zinc layer was washed several times with distilled water to remove ionic impurities from the surface, resulting in a near-spherical microstructure electrode. Finally, the electrode was cut to a suitable size for further use.

[0072] The surface of the copper foil was scanned by electron microscopy, and the results are as follows: Figure 3 It can be seen that a dense, spherical microstructure was electrodeposited on the copper foil.

[0073] The steps of S2 and S3 are described in Example 1.

[0074] Discussion on the mechanism of pressure sensors The working principle of this sensor is as follows: Figure 4-6 As shown. Figure 4 This is a cross-sectional view of the sensor. Unlike traditional co-deformation and compression strategies, this invention proposes an embedding deformation strategy. This strategy utilizes the modulus difference between a rigid microstructure and a flexible ion-embedded thin film to embed the high-modulus microstructure into a low-modulus, uniform, soft surface material under external force. The working process is as follows: Figure 5 As shown, with increasing pressure, the microstructure gradually embeds itself into the flexible ion-exchange membrane below. Since the upper and lower microstructure electrodes carry positive and negative charges respectively, contact with the ion-exchange membrane induces the aggregation of cations and anions within the membrane, forming an electric double-layer capacitance and increasing the sensor's capacitance signal (e.g., ...). Figure 6 This embedding deformation strategy can significantly reduce stress concentration points and enhance the structure's ability to withstand higher stresses, thus creating more deformable space under high-pressure operation. The high-modulus hemispherical structure is embedded into the planar elastic material under external force, resulting in localized embedding deformation. This modulus difference-induced embedding deformation strategy can significantly slow down the deformation saturation process and ensure that the contact area at the interface between the microstructure electrode and the uniform surface electrode is continuously changing, maintaining a constant contact area even under high-pressure conditions, thereby ensuring the linearity of the sensor. Simultaneously, the double-layer capacitance enables the sensor to possess high sensitivity. Therefore, the sensor can have high sensitivity and a wide linear detection range.

[0075] Pressure sensor characterization Figure 7The figure shows the pressure-capacitance performance of sensors fabricated with ion-films containing ion liquids of different mass percentages. The percentages in the figure refer to the mass percentage of the ion liquid in the ion-film. This data was tested using Sensor 1 as a representative sensor. Figure 7 It is known that the performance of the sensor can be changed by adjusting the content of the ionic liquid.

[0076] Figure 8 The figures show the pressure-capacitance performance of sensors assembled from five types of rigid microstructure electrodes in Examples 1-5, where (AE) represents the performance of the spherical microstructure electrode, irregular granular microstructure electrode, sheet-like microstructure electrode, sheet / conical microstructure electrode, and conical microstructure electrode in Examples 1-5, respectively. Devices 1-3 represent repeated experiments. The sensors fabricated from the first three types of microstructure electrodes can achieve a detection range of 1 MPa while exhibiting high sensitivity. The latter two sensors demonstrate high sensitivity in the low-pressure region (<200 kPa).

[0077] Figure 9 The following are pressure-capacitance performance graphs for the three groups of sensors in Example 1 and Comparative Examples 1-2, where 20, 35, and 50 mA·cm⁻¹ are given. -2 The curves represent Comparative Example 1, Example 1, and Comparative Example 2, respectively. When the electrodeposition time is short or the current density is low, the microstructure height / density is insufficient, and the embedding deformation is inadequate, resulting in a small deformable area inside the sensor. This makes it easy to reach deformation saturation in the low-pressure region, thus narrowing the sensor's detection range. Conversely, when the electrodeposition time is long or the current density is high, the microstructure is too dense / too tall, leading to a large embedding deformation area, which is beneficial for increasing the sensor's detection range. However, since the sensor's capacitance change mainly originates from the double-layer capacitance at the electrode-ion film interface, a large number of microstructures requires the electrode and ion film to make sufficient contact under higher pressure, resulting in a slow capacitance change. Therefore, compared to electrodes with fewer microstructures, electrodes with more microstructures will have lower sensor sensitivity. Furthermore, a higher current density does not necessarily lead to a more significant decrease in sensor sensitivity. Once the current density reaches a certain level, it does not actually affect sensor performance. Therefore, since current density has diminishing marginal returns on sensitivity and there is a performance plateau, it is only necessary to select an appropriate current density parameter to simultaneously achieve high performance and reduce current loss. In Examples 1-5 of this invention, a microstructure with "moderate height + moderate density" is obtained by adjusting parameters such as electrolyte composition, current density, deposition time, and temperature, so that the embedding process continues to occur within the target pressure range, thereby obtaining a wide linear range.

[0078] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A capacitive pressure sensor, characterized in that, It includes a dielectric layer and electrodes disposed on both sides of the dielectric layer; The dielectric layer is a flexible ionic liquid-based polymer film; The electrode includes a metal substrate; a rigid protruding microstructure is provided on one side of the metal substrate; the side of the electrode with the rigid protruding microstructure faces the dielectric layer.

2. The capacitive pressure sensor according to claim 1, characterized in that, The rigid protruding microstructure includes at least one of the following: spherical microstructure, irregular granular microstructure, sheet-like microstructure, sheet-like / conical microstructure, and conical microstructure. And / or, the metal substrate is copper foil.

3. The capacitive pressure sensor according to claim 2, characterized in that, The preparation method of the electrode with a spherical microstructure includes the following steps: using copper foil as the cathode, zinc plate as the anode, and ZnCl2-containing electrolyte as the medium, the electrode with a spherical microstructure is prepared by constant current electrodeposition. And / or, the preparation method of the electrode with sheet-like microstructure includes the following steps: using copper foil as the cathode, zinc plate as the anode, and ZnSO4-containing electrolyte as the medium, the electrode with sheet-like microstructure is deposited by constant current electrodeposition method.

4. The capacitive pressure sensor according to claim 2, characterized in that, The preparation method of an electrode with irregular granular microstructure includes the following steps: using copper foil as the cathode, zinc plate as the anode, and an electrolyte containing ZnCl2, NH4Cl and H3BO3 as the medium, a constant current electrodeposition method is used to deposit the electrode to obtain an electrode with irregular granular microstructure.

5. The capacitive pressure sensor according to claim 2, characterized in that, The preparation method of the electrode with sheet-like / conical microstructure includes the following steps: using copper foil as the cathode, nickel foam as the anode, and an electrolyte containing NiCl2, NaCl and H3BO3 as the medium, the electrode is deposited by constant current electrodeposition to obtain the electrode with sheet-like / conical microstructure. And / or, the preparation method of the electrode with the pointed cone-shaped microstructure includes the following steps: using copper foil as the cathode, nickel foam as the anode, and an electrolyte containing NiCl2, NH4Cl and H3BO3 as the medium, the electrode with the pointed cone-shaped microstructure is deposited by constant current electrodeposition.

6. The capacitive pressure sensor according to claim 1, characterized in that, The raw materials for preparing the flexible ionic liquid-based polymer film include: ionic liquid and thermoplastic polyurethane elastomer.

7. The capacitive pressure sensor according to claim 6, characterized in that, The preparation method of the flexible ionic liquid-based polymer film includes the following steps: mixing an ionic liquid and a thermoplastic polyurethane elastomer, coating the resulting mixed solution onto a substrate, and drying it to obtain the flexible ionic liquid-based polymer film.

8. The capacitive pressure sensor according to claim 7, characterized in that, The drying temperature is 60-90℃.

9. A method for manufacturing a capacitive pressure sensor according to any one of claims 1-8, characterized in that, The process includes the following steps: attaching a flexible ionic liquid-based polymer film to one side of one electrode, and then attaching another electrode to the other side of the flexible ionic liquid-based polymer film, with both sides of the flexible ionic liquid-based polymer film in contact with the rigid protruding microstructures of the electrodes, forming a three-layer structure; and then covering and encapsulating the three-layer structure to obtain the capacitive pressure sensor.

10. The application of the capacitive pressure sensor according to any one of claims 1-8 in wearable devices, intelligent robots, and medical monitoring devices.

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